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Quantification of polyhydroxyalkanoate accumulated in waste activated sludge
Ruizhe Pei1, Gerard Vicente-Venegas2, Mark C M Van Loosdrecht3
1Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, Delft 2629 HZ, the Netherlands; Wetsus, European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, Leeuwarden 8911 MA, the Netherlands.
Pilot-scale experiments show municipal waste activated sludge can accumulate significant polyhydroxyalkanoate (PHA). Quantitative microscopy and polymer mass assessment revealed the distribution and capacity of PHA storage within the biomass.
Area of Science:
- Environmental Microbiology
- Biotechnology
- Polymer Science
Background:
- Municipal waste activated sludge is a potential resource for biopolymer production.
- Polyhydroxyalkanoates (PHAs) are biodegradable polyesters with diverse applications.
- Understanding PHA accumulation dynamics in sludge is crucial for optimizing bioprocesses.
Purpose of the Study:
- To quantify polyhydroxyalkanoate (PHA) accumulation in full-scale municipal waste activated sludge at a pilot scale.
- To characterize the distribution of PHA within the biomass using advanced imaging techniques.
- To differentiate between the enrichment of PHA-storing bacteria and their individual storage capacity.
Main Methods:
- Pilot-scale cultivation of municipal waste activated sludge.
- Thermogravimetric analysis for quantifying total biomass PHA content.
- Confocal Laser Scanning Microscopy with selective staining for visualizing PHA distribution.
- Image analysis to determine the percentage of PHA-storing biomass.
- 16S rRNA analysis to assess microbial community composition.
Main Results:
- Biomass achieved up to 0.49 ± 0.03 gPHA/gVSS over 48 hours.
- Image analysis indicated approximately 55% of the sludge biomass was actively storing PHA.
- The PHA-accumulating fraction of the biomass was estimated to have a higher storage capacity (around 0.64 gPHA/gVSS).
- Microbial community structure (16S rRNA levels) did not show a clear trend during PHA accumulation.
Conclusions:
- Municipal waste activated sludge can be effectively utilized for PHA production at pilot scale.
- Quantitative microscopy combined with polymer mass assessment provides valuable insights into PHA storage dynamics.
- The study successfully distinguished between the abundance of PHA-storing bacteria and their storage efficiency.
